Index of Species Information

SPECIES:  Celtis laevigata


SPECIES: Celtis laevigata
AUTHORSHIP AND CITATION : Sullivan, Janet. 1993. Celtis laevigata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [].

ABBREVIATION : CELLAE SYNONYMS : Celtis mississipiensis Bosc. C. smallii Beadle C. laevigata var. smallii (Beadle) Sargent SCS PLANT CODE : CELA COMMON NAMES : sugarberry hackberry sugar hackberry Texas sugarberry southern hackberry lowland hackberry palo blanco TAXONOMY : The accepted scientific name for sugarberry is Celtis laevigata L. [17,59]. Recognized varieties are as follows [59]: C. l. var. texana (Scheele) Sarg. - Texas sugar hackberry C. l. var. brachyphylla Sarg. - Uvalde sugar hackberry C. l. var. anomala Sarg. - scrub sugar hackberry C. l. var. brevipes Sarg.) - Arizona sugar hackberry LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Celtis laevigata
GENERAL DISTRIBUTION : Sugarberry is native to the southeastern part of the United States, ranging south from southeastern Virginia to southern Florida; west to central Texas and including northeastern Mexico; north to western Oklahoma and southern Kansas; and east to Missouri, extreme southern Illinois, and Indiana. It occurs locally in Maryland [5,17,36]. ECOSYSTEMS : FRES12 Longleaf - slash pine FRES13 Loblolly - shortleaf pine FRES14 Oak - pine FRES15 Oak - hickory FRES16 Oak - gum - cypress FRES17 Elm - ash - cottonwood STATES : AL AR FL GA IL IN KY LA MD MS MO NC SC TN TX MEXICO BLM PHYSIOGRAPHIC REGIONS : NO-ENTRY KUCHLER PLANT ASSOCIATIONS : K084 Cross Timbers K089 Black Belt K092 Everglades K111 Oak - hickory - pine forest K112 Southern mixed forest K113 Southern floodplain forest SAF COVER TYPES : 70 Longleaf pine 75 Shortleaf pine 80 Loblolly pine - shortleaf pine 81 Loblolly pine 82 Loblolly pine - hardwood 83 Longleaf pine - slash pine 84 Slash pine 85 Slash pine - hardwood 87 Sweet gum - yellow-poplar 88 Willow oak - water oak - diamondleaf oak 89 Live oak 92 Sweetgum - willow oak 93 Sugarberry - American elm - green ash 94 Sycamore - sweetgum - American elm 95 Black willow 96 Overcup oak - water hickory 105 Tropical hardwoods 111 South Florida slash pine SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : In many areas, sugarberry occurs as scattered individuals. After disturbances, a seral sugarberry-American elm (Ulmus americana)-green ash (Fraxinus pennsylvanica) forest cover type may develop, with sugarberry as a codominant. This type intermixes with sweetgum (Liquidambar styraciflua)-willow oak (Quercus phellos) types, which contain essentially the same species in different densities. The sugarberry-American elm-green ash type occurs most often on the central coastal plain of the Gulf of Mexico, heavily concentrated on the Mississippi alluvial plain, and along major river basins [21,36]. Publications in which sugarberry is listed as a dominant or codominant include: Woody vegetation of an old-growth creekbottom forest in north-central Texas. [41] Quadrat study of a bottomland forest in St. Martin Parish, Louisiana. [50] Woody species composition of the upper San Antonio River gallery forest. [6] Productivity and composition of a baldcypress-water tupelo site and a bottomland hardwood site in a Louisiana swamp. [10] Vegetative analysis of the floodplain of the Trinity River, Texas. [42] Plant communities of the Santa Ana National Wildlife Refuge, Texas. [62] The distribution of woody species in the Guadalupe River floodplain forest in the Edwards Plateau of Texas. [20]


SPECIES: Celtis laevigata
WOOD PRODUCTS VALUE : The wood of sugarberry is close grained, soft, and of medium strength. It is used mostly for furniture but also is used for dimension stock, flooring, crating, fuel, cooperage, and fence posts [5,59]. IMPORTANCE TO LIVESTOCK AND WILDLIFE : The fruits of sugarberry are eaten by many birds, including the ring-necked pheasant, waterfowl, quail, and ruffed grouse. They are a preferred food of turkeys in fall and winter. Squirrels occasionally eat the fruit, and will also consume buds and bark, but do so rarely. Other game and nongame animals consume the fruit. Cattle will browse sugarberry heavily, especially in winter on poor ranges [12]. White-tailed deer will browse sugarberry, but it has a low preference rating [4,8]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : A study of the nutritional value of a number of fruits and nuts included sugarberry fruits in the following analysis [49]. This study reported only the combined averages for particular types of fruits and nuts. The following data are percentages of dry weight for all fleshy fruits tested, except for crude fat which is the average for drupes only: crude protein 8.4 crude fat 14.2 crude fiber 24.1 estimated true dry matter digestibility 64.4 COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : NO-ENTRY OTHER USES AND VALUES : Sugarberry is planted as an ornamental and as a street tree [5]. OTHER MANAGEMENT CONSIDERATIONS : In dense even-aged stands, sugarberry will self-prune and produce a straight stem [5]. In cottonwood (Populus spp.) stands on alluvium, sugarberry (usually with poor growth forms) will take over openings created when cottonwoods are cut, and control sites that managers would prefer to be in more valuable species [30]. On a site that was logged then seeded with Nuttall oak (Quercus nuttallii), sugarberry (probably carried in by animals) naturally established in sufficient numbers to make up one of four species accounting for 83 percent of stems [33,39]. Sugarberry is susceptible to damage by ice, which breaks main stems and branches [5]. Defoliation of sugarberry by hackberry butterfly (Asterocampa celtis) has been reported, though no tree death or crown die-back was observed. Hackberry butterfly can be controlled by spraying trees with insecticides [5]. Sugarberry is used as an ornamental, even though leaf leachate can reduce growth of grasses under the trees due to the presence of ferulic, caffeic, and p-coumaric acids [5]. Good stands of sugarberry are able to establish naturally after logging [22]. In a study of logging practices in Mississippi, sugarberry reached the highest densities in regeneration after all sawtimber-sized stems were removed and either all stems greater than 2 inches in d.b.h. (5 cm) were injected with 2,4-D or stems of desirable species left untreated with 2,4-D. Sugarberry was considered a desirable species in this study [29]. Seven years after clearcutting on a site where sugarberry was a canopy dominant, sugarberry accounted for 32 percent of total regeneration stems [23]. After patch clearcutting, sugarberry dominated both sapling and seedling regeneration on a site where, prior to harvest, it had been second in basal area (after sweetgum) [25]. Sugarberry has no major diseases of the twigs and leaves, but eastern mistletoe (Phoradendron flavescens) may cause serious damage in the western part of sugarberry's range [5].


SPECIES: Celtis laevigata
GENERAL BOTANICAL CHARACTERISTICS : Sugarberry is a moderately tall (60 to 100 feet [18-30 m]), native deciduous tree [2,5,36]. Mature trees are typically 18 inches (46 cm) in d.b.h., 80 feet (24 m) tall, with 30 feet (9 m) clear of branches in good stands [36]. The crown is spreading and round-topped or oblong. The bark of young trees is gray and smooth; mature trees develop corky outgrowths that are scattered to dense with smooth areas in between [15]. The roots of sugarberry are relatively shallow; it does not form a distinct taproot and has only average resistance to windthrow. Sugarberry has a moderately long life span, not usually living over 150 years [5]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Sexual reproduction: Sugarberry is polygamo-monoecious [2,5]. Individuals usually first produce seeds at 15 years; optimum seedbearing years are from 30 to 70 years of age. Good seed crops are produced most years, some individuals produce good crops every year. There are approximately 2,000 to 2,400 cleaned seeds per pound (4,400- 5,300/kg) [5]. Seeds have an innate dormancy, requiring cold stratification at 41 degrees Fahrenheit ( 5 deg C) for 60 to 90 days [2]. Vora [60] found that sugarberry seeds germinated best with no treatments other than cold stratification (i.e. acid scarification or gibberellic acid addition). Sugarberry seeds are dispersed by mammals, birds and by water. Seedlings are intolerant of flooding [5,36]. Sugarberry tends to grow slowly; the average 10-year diameter increase in natural stands is 1.5 inches (3.8 cm). The best growth rates are found in dominant trees at 2.5 inches (6.4 cm) in 10 years [36]. Vegetative reproduction: Sugarberry can be propagated by cuttings. Small stumps sprout readily [5,36]. SITE CHARACTERISTICS : Sugarberry is found in moist alluvial woods and slough margins (but not deep swamps) up to 600 feet (180 m) elevation [15,43]. It also occurs on upland sites, although rarely. It occurs on any soil type with fair drainage, from sandy loams and rocky or alluvial soils to heavy black clay [47]. Sugarberry is most often found on clay soils in the orders Iceptisols and Entisols on broad flats or shallow sloughs within the floodplains of major rivers, and on deep moist soils derived from limestones, but will grow under a considerable range of soil and moisture conditions [5]. Sugarberry cannot tolerate prolonged flooding or water-saturated soils [28]. Hook [27] listed sugarberry as weakly tolerant to waterlogging, and capable of living from seedling to maturity in soils temporarily waterlogged for 1 to 4 weeks of the year, or about 10 percent of the growing season. In forested wetlands sugarberry grows best in the drier areas. Rising water levels (due to sea level rise, flooding, impoundments etc.) will reduce sugarberry basal area in these forests [10]. Sugarberry occurs in cedar (Jumiperus spp.) glades in the Nashville basin, Tennessee, in mesophytic forests of the Mississippi embayment section, and in the Oachita mountains of Louisiana on elevated rocky surfaces subject to frequent floods [3]. Sugarberry is present as an occasional component of hydric hammocks in Florida [58]. Sugarberry is found in humid climates, except in the extreme western portion of its range in Texas and Oklahoma. Average annual precipitation ranges from 20 to 60 inches (510-1,520 mm). Summer temperatures average 80 degrees Fahrenheit (27 deg C) with extremes of 115 degrees Fahrenheit (46 deg C), and temperatures average 30 to 50 degrees Fahrenheit (-1 to 10 deg C) with extremes of -20 degreees Fahrenheit (-29 deg C). The average frost-free period ranges from 150 to 270 days [5,36]. Overstory associates not listed in Distribution and Occurrence include winged elm (Ulmus alata), cedar elm (U. crassifolia), water oak (Quercus nigra), southern red oak (Q. falcata), blackgum (Nyssa sylvatica), persimmon (Diospyros virginiana), honeylocust (Gleditsia tricantuos), red maple (Acer rubrum), boxelder (A. negundo), pecan (Carya illinoensis), bumelia (Bumelia lanuginosa), persimmon (Diospyros virginiana), and red mulberry (Morus rubra). Shrub associates include swamp-privet (Forestiera acuminata), roughleaf dogwood (Cornus drummondii), swamp dogwood (C. stricta), hawthorn (Crataegus spp.), and buttonbush (Cephalanthus occidentalis) [5,7,19,36,45]. Lianas occurring with sugarberry include eastern poison-ivy (Toxicodendron radicans) [19]. SUCCESSIONAL STATUS : Facultative Seral Species Seedlings of sugarberry can establish under most stands of southern bottomland hardwoods; sugarberry is shade tolerant. It will respond when released, and can outgrow more desirable forest species. When established in the understory it has a very poor form (limby, short- boled, crooked or forked) [5,36]. Sugarberry will naturally invade oak plantations, establishing at a rate of up to 43 stems per acre (105/ha) on 4- to 8-year-old sites [1]. Sugarberry commonly follows eastern cottonwood (Populus deltoides var. deltoides) and black willow (Salix nigra) in succession on new land created by rivers [31,48,54]. In succession on land disturbed by gravel pit operations, sugarberry codominated 47-year-old sites with eastern redcedar (Juniperus virginiana) but did not occur in large numbers on younger sites, and may be replaced by winged elm and post oak (Quercus stellata) on more advanced sites [40]. On Florida tree hammocks, disturbances such as fire, hurricanes or logging that do not destroy the roots of young hardwoods are likely to result in canopies containing sweetgum, hornbeam (Ostrya virginiana), oaks (Quercus spp.), and sugarberry [58]. In a well documented series of studies, Van Auken, Bush and their associates [6,7,53,55,56,57] have demonstrated that sugarberry is an important species in secondary succession on terraces of the San Antonio River in Texas. Abandoned farmland is colonized first by huisache (Acacia smallii), a light-requiring leguminous shrub. Sugarberry is present in early seres, but its growth is suppressed by the low nitrogen levels of the soils (but not, as is often the case, by the low light levels). In fact, sugarberry grows better under huisache canopies than in the open. As huisache matures, the soil nitrogen levels increase, and sugarberry grows faster and eventually overtops huisache, which dies out due to high nitrogen and low light levels. Sugarberry either remains dominant, or is eventually overtopped by other tolerant hardwoods. They conclude that sugarberry is a late successional species that needs high soil nitrogen, and is capable of growing in shade, but can grow in distrubed areas or grasslands at reduced rates depending on the presence of competition and soil nitrogen levels. Old-growth stands may include sugarberry as an important overstory species [41]. However, Robertson and Weaver [46] found that in an Illinois old-growth stand of sweetgum, green ash, and red maple, sugarberry was represented in the overstory but not in the reproduction layers (no seedlings or saplings). An adjacent plot in the later stages of secondary succession (about 75 years old) had some seedlings, but no saplings in the reproduction layer. Both the old-growth (implied climax vegetation) and the seral plots had similar basal areas of mature sugarberry. One can infer from these reports that perhaps sugarberry regeneration does not occur at a rate sufficient to maintain its numbers. Once the canopy is mature and other tolerant hardwoods are recruited, sugarberry numbers will decrease. SEASONAL DEVELOPMENT : Sugarberry flowers when the leaves first appear in spring, from March to May, depending on latitude. Fruit appears in July and August, ripening into October. The fruit is retained on the tree until midwinter [2]. Most or all leaves are lost by mid-December in the Rio Grande Valley, Texas [63].


SPECIES: Celtis laevigata
FIRE ECOLOGY OR ADAPTATIONS : The bark of sugarberry is thin and easily damaged by fire. When top-killed, sugarberry will sprout from the root collar [5]. Sugarberry occurs in areas that have undergone a shift from grassland to hardwoods (central Texas and western Oklahoma) or from pines to hardwoods as a result of fire suppression [26]. The moist bottomlands in which sugarberry occurs do not have frequent fire regimes. FIRE REGIMES : Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes". POSTFIRE REGENERATION STRATEGY : Tree with adventitious-bud root crown/root sucker Ground residual colonizer (on-site, initial community) Secondary colonizer - off-site seed


SPECIES: Celtis laevigata
IMMEDIATE FIRE EFFECT ON PLANT : Light-severity fires will kill or top-kill seedlings and saplings of sugarberry, and top-kill larger trees; severe fires may kill even the largest trees [5]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Fire-damaged seedlings and saplings sprout from the root collar [5]. After an April wildfire in Texas that top-killed all vegetation, sugarberry was observed to be sprouting from the root collar by July [61]. Wounding by fire increases susceptibility to butt rot (any of 30 species of Fomes, Polyporus, Hericium or Pleurotus). In a study of 55 years of postfire succession in a Florida mixed hardwood forest, sugarberry, while not an important species, increased in frequency [26]. Sugarberry is often a component of areas that have undergone some type of disturbance, including fire, although it is not an initial colonizer of disturbed areas (usually establishing by 4 or 5 years) [33]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Sugarberry occurs as scattered individuals in Florida pine flatwoods that are usually maintained by fire. When fire is eliminated, succession usually proceeds to either southern mixed hardwoods or bayhead communities, with a concomitant increase in basal area of sugarberry [38].


SPECIES: Celtis laevigata
REFERENCES : 1. Allen, James A. 1990. Establishment of bottomland oak plantations on the Yazoo National Wildlife Refuge Complex. Southern Journal of Applied Forestry. 14(4): 206-210. [14615] 2. Bonner, F. T. 1974. Celtis L. Hackberry. In: Schopmeyer, C. S., technical coordinator. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 298-300. [7579] 3. Braun, E. Lucy. 1950. Deciduous forests of eastern North America. Philadelphia, PA: Blakiston Books. [pages unknown]. [19812] 4. Bryant, F. C.; Kothmann, M. M. 1979. Variability in predicting edible browse from crown volume. Journal of Range Management. 32(2): 144-146. [10292] 5. Burns, Russell M.; Honkala, Barbara H., tech. coords. 1990. Silvics of North America. Vol 2. Hardwoods. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service. 877 p. [13955] 6. Bush, J. K.; Van Auken, O. W. 1984. Woody species composition of the upper San Antonio River gallery forest. Texas Journal of Science. 36(2&3): 139-148. [12481] 7. Bush, J. K.; Van Auken, O. W. 1986. Changes in nitrogen, carbon, and other surface soil properties during secondary succession. Soil Science Society of America Journal. 50: 1597-1601. [19805] 8. Chamrad, Albert D.; Box, Thadis W. 1968. Food habits of white-tailed deer in south Texas. Journal of Range Management. 21: 158-164. [10857] 9. Collins, Scott L.; Klahr, Sabine C. 1991. Tree dispersion in oak-dominated forests along an environmental gradient. Oecologia. 86(4): 471-477. [17584] 10. Conner, W. H.; Day, J. W., Jr. 1976. Productivity and composition of a baldcypress-water tupelo site and a... American Journal of Botany. 63: 1354-1364. [19807] 11. Conner, William H.; Day, John W., Jr. 1989. Responses of coastal wetland forests to human and natural changes in the environment with emphasis on hydrology. In: Hook, Donal D.; Lea, Russ, eds. The forested wetlands of the southern United States: Proceedingsl of the symposium; 1988 July 12-14; Orlando, FL. Gen. Tech. Rep. SE-50. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 34-43. [9227] 12. Crawford, Hewlette S.; Kucera, Clair L.; Ehrenreich, John H. 1969. Ozark range and wildlife plants. Agric. Handb. 356. Washington, DC: U.S. Department of Agriculture, Forest Service. 236 p. [18602] 13. Daubenmire, Rexford. 1990. The Magnolia grandiflora-Quercus virginiana forest of Florida. American Midland Naturalist. 123: 331-347. [10871] 14. Dittberner, Phillip L.; Olson, Michael R. 1983. The plant information network (PIN) data base: Colorado, Montana, North Dakota, Utah, and Wyoming. FWS/OBS-83/86. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 786 p. [806] 15. Duncan, Wilbur H.; Duncan, Marion B. 1988. Trees of the southeastern United States. Athens, GA: The University of Georgia Press. 322 p. [12764] 16. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905] 17. Fernald, Merritt Lyndon. 1950. Gray's manual of botany. [Corrections supplied by R. C. Rollins]. Portland, OR: Dioscorides Press. 1632 p. (Dudley, Theodore R., gen. ed.; Biosystematics, Floristic & Phylogeny Series; vol. 2). [14935] 18. Fisher, Richard F. 1980. Allelopathy: a potential cause of regeneration failure. Journal of Forestry. 78: 1980. [9049] 19. Fitzgerald, Charles H.; Belanger, Roger P.; Lester, William W. 1975. Characteristics and growth of natural green ash stands. Journal of Forestry. 73: 486-488. [5122] 20. Ford, Allen L.; Van, Auken, O. W. 1982. The distribution of woody species in the Guadalupe River floodplain forest in the Edwards Plateau of Texas. Southwestern Naturalist. 27(4): 383-392. [19806] 21. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others]. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998] 22. Georgia Chapter, Society of American Foresters. 1979. Silvicultural guidelines for forest owners in Georgia. Georgia Forest Research Paper 6. [Place of publication unknown]: Georgia Forestry Commission, Research Division. 35 p. [15405] 23. Golden, Michael S.; Loewenstein, Edward F. 1991. Regeneration of tree species 7 years after clearcutting in a river bottom in central Alabama. In: Coleman, Sandra S.; Neary, Daniel G., compilers. Proceedings, 6th biennial southern silvicultural research conference: Volume I; 1990 October 30 - November 1; Memphis, TN. Gen. Tech. Rep. SE-70. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 76-83. [17464] 24. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603] 25. Gresham, Charles A. 1985. Pine and hardwood regeneration alternatives for harvested bottomland hardwood stands. In: Shoulders, Eugene, ed. Proceedings of the Third Biennial Southern Silvicultural Research Conference; 1984 November 7 - November 8; Atlanta. General Technical Report SO-54. New Orleans: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station: 87-92. [7387] 26. Hartnett, David C.; Krofta, Douglas M. 1989. Fifty-five years of post-fire succession in a southern mixed hardwood forest. Bulletin of the Torrey Botanical Club. 116(2): 107-113. [9153] 27. Hook, D. D. 1984. Waterlogging tolerance of lowland tree species of the South. Southern Journal of Applied Forestry. 8: 136-149. [19808] 28. Hosner, John F.; Boyce, Stephen G. 1962. Tolerance to water saturated soil of various bottomland hardwoods. Forest Science. 8(2): 180-186. [18950] 29. Hurst, George A.; Bourland, Thomas R. 1980. Hardwood density and species composition in bottomland areas treated for regeneration. Southern Journal of Applied Forestry. 4(3): 122-127. [7839] 30. Johnson, Robert L. 1965. Regenerating cottonwood from natural seedfall. Journal of Forestry. 63(1): 33-36. [6290] 31. Johnson, R. L.; Shropshire, F. W. 1983. Bottomland hardwoods. In: Burns, Russell M., tech. comp. Silvicultural systems for the major forest types of the United States. Agric. Handb. 445. Washington, DC: U.S. Department of Agriculture, Forest Service: 175-179. [18953] 32. Kartesz, John T.; Kartesz, Rosemarie. 1980. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. Volume II: The biota of North America. Chapel Hill, NC: The University of North Carolina Press; in confederation with Anne H. Lindsey and C. Richie Bell, North Carolina Botanical Garden. 500 p. [6954] 33. Krinard, R. M.; Johnson, R. L. 1981. Description and yields of an 11-year-old hardwood stand on Sharkey clay soil. Res. Note SO-265. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 2 p. [4229] 34. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 77 p. [1384] 35. Lyon, L. Jack; Stickney, Peter F. 1976. Early vegetal succession following large northern Rocky Mountain wildfires. In: Proceedings, Tall Timbers fire ecology conference and Intermountain Fire Research Council fire and land management symposium; 1974 October 8-10; Missoula, MT. No. 14. Tallahassee, FL: Tall Timbers Research Station: 355-373. [1496] 36. McKnight, J. S. 1965. Sugarberry. Agric. Handb. 271. Washington, DC: U.S. Department of Agriculture, Forest Service. 2 p. [5123] 37. McWilliams, William H.; Rosson, James R., Jr. 1990. Composition and vulnerability of bottomland hardwood forests of the Coastal Plain Province in the south central United States. Forest Ecology and Management. 33/34: 485-501. [11814] 38. Monk, Carl D. 1968. Successional and environmental relationships of the forest vegetation of north central Florida. American Midland Naturalist. 79(2): 441-457. [10847] 39. Newling, Charles J. 1990. Restoration of bottomland hardwood forests in the lower Mississippi Valley. Restoration & Management Notes. 8(1): 23-28. [14611] 40. Nixon, Elray S. 1975. Successional stages in a hardwood bottomland forest near Dallas, Texas. Southwestern Naturalist. 20: 323-335. [12250] 41. Nixon, E. S.; Ward, J. R.; Fountain, E. A.; Neck, J. S. 1991. Woody vegetation of an old-growth creekbottom forest in north-central Texas. Texas Journal of Science. 43(2): 157-164. [15407] 42. Nixon, Elray S.; Willett, R. Larry. 1974. Vegetative analysis of the floodplain of the Trinity River, Texas. Contract No. DACW6-74-C-0030. Prepared for U.S. Army Corps of Engineers, Fort Worth District, Fort Worth, Texas. [Place of publication unknown]: [Publisher unknown]. 267 p. On file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. [20420] 43. Radford, Albert E.; Ahles, Harry E.; Bell, C. Ritchie. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press. 1183 p. [7606] 44. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843] 45. Risser, Paul G.; Rice, Elroy L. 1971. Phytosociological analysis of Oklahoma upland forest species. Ecology. 52(5): 940-945. [7868] 46. Robertson, Philip A.; Weaver, George T.; Cavanaugh, James A. 1978. Vegetation and tree species patterns near the northern terminus of the southern floodplain forest. Ecological Monographs. 48(3): 249-267. [10381] 47. Simpson, Benny J. 1988. A field guide to Texas trees. Austin, TX: Texas Monthly Press. 372 p. [11708] 48. Shelford, V. E. 1954. Some lower Mississippi valley flood plain biotic communities; their age and elevation. Ecology. 35(2): 126-142. [4329] 49. Short, Henry L.; Epps, E. A., Jr. 1976. Nutrient quality and digestibility of seeds and fruits from southern forests. Journal of Wildlife Management. 40(2): 283-289. [10510] 50. Thieret, John W. 1971. Quadrat study of a bottomland forest in St. Martin Parish, Louisiana. Castanea. 36: 174-181. [9923] 51. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 1974. Wood handbook: wood as an engineering material. Agric. Handb. No. 72. Washington, DC. 415 p. [16826] 52. U.S. Department of Agriculture, Soil Conservation Service. 1982. National list of scientific plant names. Vol. 1. List of plant names. SCS-TP-159. Washington, DC. 416 p. [11573] 53. Van Auken, O. W.; Bush, J. K. 1985. Secondary succession on terraces of the San Antonio River. Bulletin of the Torrey Botanical Club. 112(2): 158-166. [19810] 54. Van Auken, O. W.; Bush, J. K. 1988. Dynamics of establishment, growth, and development of black willow and cottonwood in the San Antonio River Forest. Texas Journal of Science. 40(3): 269-277. [11138] 55. Van Auken, O. W.; Bush, J. K. 1991. Influence of shade and herbaceous competition on the seedling growth of two woody species. Madrono. 38(3): 149-157. [16572] 56. Van Auken, O. W.; Gese, E. M.; Connors, K. 1985. Fertilization response of early and late successional species: Acacia smallii and Celtis laevigata. Botanical Gazette. 146(4): 564-569. [19811] 57. Whisenant, Steven G.; Uresk, Daniel W. 1989. Burning upland, mixed prairie in Badlands National Park. Prairie Naturalist. 21(4): 221-227. [11151] 58. Vince, Susan W.; Humphrey, Stephen R.; Simons, Robert W. 1989. The ecology of hydric hammocks: A community profile. Biological Rep. 85(7.26). Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service, Research and Development. 82 p. [17977] 59. Vines, Robert A. 1960. Trees, shrubs, and woody vines of the Southwest. Austin, TX: University of Texas Press. 1104 p. [7707] 60. Vora, Robin S. 1989. Seed germination characteristics of selected native plants of the lower Rio Grande Valley, Texas. Journal of Range Management. 42(1): 36-40. [6101] 61. Vora, Robin S. 1989. Fire in an old field adjacent to a sabal palm grove in south Texas. Texas Journal of Science. 41(1): 107-108. [7063] 62. Vora, Robin S. 1990. Plant communities of the Santa Ana National Wildlife Refuge, Texas. Texas Journal of Science. 42(2): 115-128. [11944] 63. Vora, Robin S. 1990. Plant phenology in the lower Rio Grande Valley, Texas. Texas Journal of Science. 42(2): 137-142. [11832] 64. Williams, Robert D.; Hanks, Sidney H. 1976. Hardwood nurseryman's guide. Agric. Handb. 473. Washington, DC: U.S. Department of Agriculture, Forest Service. 78 p. [4182] 65. Wheeler, E. A.; LaPasha, C. A.; Miller, R. B. 1989. Wood anatomy of elm (Ulmus) and hackberry (Celtis) species native to the United States. International Association of Wood Anatomy Bulletin. 10(1): 5-26. [11552] 66. Wright, Henry A.; Bailey, Arthur W. 1982. Fire ecology: United States and southern Canada. New York: John Wiley & Sons. 501 p. [2620]